If you flip three fair coins, what is the probability that you'll get all three heads?
Solution: $\text{Probability} = \dfrac{\text{Favorable outcomes}}{\text{Total possible outcomes}}$ If you flip three coins, there are $2$ possible outcomes for each individual flip, so there are $2\times2\times2=8$ total possible outcomes. Since the coin is fair, each outcome is equally likely. Each path through the tree represents one outcome. The green path shows the $1$ favorable outcome. $\text{H}$ $\text{T}$ $\text{First}$ $\text{H}$ $\text{T}$ $\text{H}$ $\text{T}$ $\text{Second}$ $\text{H}$ $\text{T}$ $\text{H}$ $\text{T}$ $\text{T}$ $\text{H}$ $\text{T}$ $\text{H}$ $\text{Third}$ The probability of getting three heads is $1$ out of $8$, or $\dfrac18$.